A universal smartphone add-on for portable spectroscopy and polarimetry: iSPEX 2

TL;DR

The paper introduces iSPEX 2, a low-cost, smartphone-compatible spectropolarimeter for environmental remote sensing, enabling scalable citizen science measurements of aerosols and water reflectance.

Contribution

It presents a universal, modular smartphone add-on for spectropolarimetry, combining hardware design and data processing for accessible environmental sensing.

Findings

Prototype manufacturing via injection molding and 3D printing.

Active development of a dedicated smartphone app for data acquisition.

Plans for calibration, validation, and scientific applications in 2020.

Abstract

Spectropolarimetry is a powerful technique for remote sensing of the environment. It enables the retrieval of particle shape and size distributions in air and water to an extent that traditional spectroscopy cannot. SPEX is an instrument concept for spectropolarimetry through spectral modulation, providing snapshot, and hence accurate, hyperspectral intensity and degree and angle of linear polarization. Successful SPEX instruments have included groundSPEX and SPEX airborne, which both measure aerosol optical thickness with high precision, and soon SPEXone, which will fly on PACE. Here, we present a low-cost variant for consumer cameras, iSPEX 2, with universal smartphone support. Smartphones enable citizen science measurements which are significantly more scaleable, in space and time, than professional instruments. Universal smartphone support is achieved through a modular hardware design and SPECTACLE data processing. iSPEX 2 will be manufactured through injection molding and 3D printing. A smartphone app for data acquisition and processing is in active development. Production, calibration, and validation will commence in the summer of 2020. Scientific applications will include citizen science measurements of aerosol optical thickness and surface water reflectance, as well as low-cost laboratory and portable spectroscopy.